The BioCycle Study was a prospective longitudinal cohort study comprising 259 women aged 18 to 44 years (98% follow-up rate) followed for two menstrual cycles (2005-2007). The study was designed to better understand menstrual cycle function and the intricate relationships between reproductive hormone levels and oxidative stress. Since completion of the study, much progress has been made in the analysis of the BioCycle Study data. To date, over 80 papers have been published. The BioCycle Study has contributed substantially to the fields of nutritional, environmental, and social epidemiology, offering valuable insights into various factors associated with premenopausal womens reproductive and cardio-metabolic health. In particular, several dietary factors have been evaluated with regard to their associations with reproductive hormones and ovulation, including diary food intake (Kim et al. Journal of Nutrition 2017). These findings have highlighted the important role of diet in reproductive function. Further research evaluating potential environmental factors, including blood lead, cadmium, and mercury, found that lead levels were associated with increased homocysteine, a marker of inflammation, which has potential implications for cardiovascular disease later in life (Pollack et al. Environmental Health 2017). In addition, it was also observed that plasma homocysteine was associated with altered hormone levels throughout the menstrual cycle, as well as with an increased risk of sporadic anovulation (Michels et al. Human Reproduction 2017). Further research into the mechanisms driving these associations is needed to understand the potential implications for women's health. Overall, this body of work has been influential in describing not only the short-term impact of diet and lifestyle on hormonal function and markers of menstrual cycle dysfunction (e.g., anovulation, luteal phase deficiency, and abnormal menses) but their potential long-term impact on chronic disease risk. The team intends to build upon its current findings from the BioCycle Study to fill critical research gaps in its quest to answer important public health questions for women of reproductive age.